Heat oil in a pressure cooker over medium heat to about 400°F In a small bowl, beat the egg and stir in milk. In a separate bowl, combine flour, sugar, pepper and salt. Dip each piece of chicken in milk until it is fully moistened. Roll the moistened chicken in the flour mixture until completely coated. Drop chicken into the hot oil and close pressure cooker. When steam starts shooting through pressure release, set timer for 3 1/2 minute.